Control system for refrigeration and heat pump equipment



y 20, 1965 c. J. WQLFF 3,195,319

CONTROL SYSTEM FOR REFRIGERATION AND HEAT PUMP EQUIPMENT Filed Jan. 29, 1963 3 Sheets-Sheet 1 r z 3 Ji Q; eo

v WMJW H,

4%, INVENTOR BY; W M

July 20, 1965 c. J. WOLFF 3,195,319

CONTROL SYSTEM FOR REFRIGERATION AND HEAT PUMP EQUIPMENT Filed Jan. 29, 1963 s Sheets-Sheet 2 F l s. 2

70 5' -it d WiTVZENTO? 7 BY M July 20, 1965 c. J. WOLFF 3,195,319 CONTROL SYSTEM FOR REFRIGERATION AND HEAT PUMP EQUIPMENT Filed Jan. 29, 1965 5 Sheets-Sheet 3 U 23 Q. 29 I7 28 2? 3O 60 'F I V l"ll\\\ I0 I I2 26 3| FIG. 4

United States Patent 3,195,319 CONTRGL SYSTEM FOR REFREGERATION AND HEAT PUMP EQUIPMENT Charles J. Wolff, deceased, late of 720 Wiltshire, San

Antonio 9, Tex, by Marie Tillitt Wold, executrix, San

Antonio, Tex.

Fiied Jan. 29, 1963, Ser. No. 255,427 9 Claims. (Cl. 62-196) This invention relates to improvements in refrigeration and heat pump apparatus operating upon the compression-condensation-expansion-evapora-tion cycle. It is especially directed to control systems for such apparatus for maintaining adequate pressure upon liquid refrigerant flowing through a pressure-reducing means under conditions of excess condenser capacity.

Refrigeration and heat pump systems containing a refrigerant and including a compressor, a condenser, a receiver located at a level lower than the condenser, a pressure-reducing device, and an evaporator connected in sequence by suitable piping frequently fail to operate satisfactorily under conditions of excess condenser capacity. Excess condenser capacity often occurs when there is a marked decrease in the temperature of the fluid used to cool the condenser, as for example in an air-cooled condenser of a refrigeration system, during cold weather operation.

Excess condenser capacity results in reduction in pressure in the condenser and in a receiver usually included in the system between the condenser and a pressure-reducing device such as a pressure-reducing valve or capillary located in a line arranged to conduct liquid refrigerant from the receiver to an evaporator. Reduction of pressure on the upstream side of the pressure-reducing device frequently is so great that normal flow of refrigerant through the pressure-reducing device cannot be maintained.

Under these conditions, liquid accumulates or stacks up in the condenser and/or receiver, and a relatively small amount of the total refrigerant in the system is present in the evaporator and compressor so that low pressure at the intake of the compressor decreases compressor efficiency, and in fact the entire system becomes quite inefi'icient.

The ineificiency in operation can be temporarily corected by adding refrigerant to the system. This additional liquid refrigerant fills the condenser, thereby reducing the condensers capacity to remove heat from the gaseous refrigerant, resulting in increased head pressure and establishing a normally functioning refrigeration system. When normal summer ambient conditions prevail, the excess refrigerant must be removed from the system or stored in a receiver of excessive capacity. It is dilficult .to start the refrigerant on cycle under excess condenser capacity conditions since low pressure at the inlet of the compressor results in abnormally low pressure and low temperature of an effluent of hot compressed gas issuing from the compressor outlet; and the excess capacity of the condenser results in cooling and condensing the efiiuent to such degree that the pressure in the receiver is not sufiicient to force the liquid refrigerant through the pressure-reducing device at a rate of flow sutlicient to start efficient operation.

It is an object of this invention to provide an improved control system for refrigerating or heat pump equipment which is effective to maintain pressure of refrigerant in a condenser and receiver in a selected normal range under conditions of excess condenser capacity without accumulation of a large excess of liquid refrigerant in the condenser or receiver.

Another object is to provide such improved control 3,195,319 Patented July 20, 1965 'ice system wherein the rate of heat transfer between refrigerant and wall-s of a condenser is lowered by decrease in turbulence of refrigerant in the condenser under conditions of excess condenser capacity.

Another object is to provide such improved control system wherein liquid refrigerant at a low temperature in a receiver is subjected to pressure from gaseous refrigerant at higher temperature.

Another object is to provide such an improved control system wherein addition of refrigerant under conditions of excess condenser capacity is unnecessary.

Another object is to provide such an improved control system wherein excess receiver capacity is unnecessary.

Another object is to provide such improved control system which provides easy start-up of refrigeration and heat pump equipment under conditions of excess conv denser capacity.

Another object is to provide such improved control system which doe not require hydrostatic head from liquid accumulated in a condenser or receiver to enable start-up under conditions of excess condenser capacity.

Another object is to provide a control system of the above type which is highly etlicient in defrosting refrigeration equipment under low ambient temperature conditions.

Other objects, advantages and features of this invention will be apparent to one skilled in the art upon a consideration of the written specification, the attached claims and the annexed drawings.

The present invention includes valve means for dividing an efiluent of hot, gaseous refrigerant from an outlet of a compressor into two streams, namely, a first and a second stream, on reduction of pressure in a receiver below a selected normal value; and for modulating the proportions of total efiluent distributed into the two streams according to the degree of reduction in receiver pres-sure below the normal value.

This means may include one or more valves, manually or automatically operable; but it is preferred that it include a single modulating valve responsive to receiver pressure, and further preferred that the valve have an inlet port connected by a pipe to the compressor outlet, a first outlet port connected through suitable piping to an inlet of a condenser, a second outlet port connected to a bypass line communicating with an upper part of the receiver above a body of liquid normally present in the receiver, suitable fiowways in the valve between the inlet port and the first and second outlet port-s, valve seats and cooperating valve-closure member-s controlling fiow through the fiowways from the inlet port to each of the first and second outlet ports, and an actuator responsive to receiver pressure arranged to move the valveclosure members toward and away from valve-closing position in relationship to the respective valve seats.

Flow-restricting means are provided in the modulating valve to partially restrict flow through the first outlet port while at all times permitting some flow therethrough. This means is illustrated as the valve-closure member and corresponding valve seat which control flow between the inlet and the first outlet port and which are arranged to provide free flow from the inlet port to the first outlet port and to the condenser when receiver pressure is normal, but the valve is so arranged that this passageway is not completely closed when receiver pressure falls so that the flowway is always partially open even when the valve-closure member is moved to its maximum distance of travel in valve-closing direction. This arrangement provides at least a selected minimum flow of hot gaseous efiluent to the condenser inlet at all times. The valve-closure member and corresponding valve seat controlling flow between the inlet port and the second outlet port are arranged to close the flowway entirely when receiver pressure is above the selected normal value so that, when this valve-closure member is seated, all efiluent from the compressor is directed to the condenser inlet.

The valve actuator preferably is a spring-loaded bellows connected to a common valve stem carrying both valve-closure members although a spring-loaded diaphragm of pressure-charged bellows or diaphragm may be used if desired. The spring-loaded bellows is preferred because of its cheapness and ease of adjustment under field conditions. However constructed, the means for dividing and modulating the efiiuent into two streams is located upstream of the condenser in piping connecting the compressor outlet with the condenser inlet.

As stated above, a bypass line connecting with the second outlet port communicates with the receiver at a point above the normal level of a body of liquid refrigerant contained in the receiver. Asa result, h-ot gaseous effluent when supplied to the receiver overlies the body of liquid refrigerant; andsince there is little turbulence in gas above the liquid and gaseous refrigerants are poor conductors of heat, the rate of heat exchange between the hot gas and the colder liquid is low. course condensation at the gas-liquid interface and continuous, relatively slow movement of gas downward; but

the compressor continuously supplies hot gas through" the valve means at a rate of flow sufficient to maintain gas in the upper part of the receiver at a temperature substantially higher than temperature of the liquid. Pressure from this hot gas is exerted through the successively cooler layers of gas upon the surface of the liquid and so maintains a substantially higher pressure in the receiver than would be present if the gas were admitted in such manner as to come immediately to a temperature approaching that of the liquid. At the same time liquid refrigerant is withdrawn through the pressure-reducing device, as described below, at a rate which preventsit from becoming heated to the temperature of the gas.

Means are disposed to at least restrict fiow into the condenser outlet. Thus a line connects the upper part of the receiver with the outlet of the condenser. This line contains a check valve arranged so that liquid may flow from the condenser through the check valve to the receiver. The check valve is responsive to condenser pressure and is arranged to openwhen condenser pressure is substantially equalizedwith receiver pressure. The condenser may be located above the receiver to provide for gravity flow of liquid, if desired, or the condenser may be on the same level with or below the receiver.

tween the condenser and receiver.

A restricted passageway communicating with the interior of the piping above and below the check valve is provided so that closure of the check valve does not entirely out off communication between the condenser outlet and the upper part of the receiver. The restricted passageway may be constructed as a bleed passageway.

through the check-value-closure member, but may be a passageway in the check. valve body or even a small pipe bypassing the check valve. This restricted passageway serves as a means for applying pressure from hot gas in the upper part of the receiver to oppose flow of.

the first stream of compressor efiluent into the inlet of the condenser when the check valve is closed, thus substantially equalizing pressure in the receiver with pressure at the condenser outlet. 7

The restricted passageway, whether constructed as a bleed opening in a valve-closure member or as a small passageway or pipe bypassing the check-valve-closure member and valve seat, cooperates with the valve means for dividing and modulating the efiluent and the check valve under conditions of excess condenser capacity to effectively reduce heat transfer in the condenser. It has been found that back pressure from hot gas in the receiver applied in this manner effectively reduces turbu- There is'of In the latter case flow is produced by pressure differential be-- 4 lence in the condenser. That part of the efiluent introduced as the first stream into the inlet of the condenser against back pressure of hot gas from the receiver flows through the condenser slowly and in a less turbulent manner. As was stated above, the refrigeration gases are poor conductors of heat so that only the gas in immediate contact with the Walls of the condenser is cooled and condensed. Cooling of the entire stream of gas is less rapid and efiicient when turbulence of refrigerant in the condenser is decreased.

All liquid condensed in the condenser flows downward and is drained into the receiveroand drips into the body of liquid in the lower part of the receiver when pressure in the condenser is equalized with receiver pressure without causing any great turbulence in hot gas overlying liquid in the receiver.

The choking effect of the'restricted passageway permits receiver pressure to build up while a relatively small part of the hot gas from the upper part of the receiver flows through the small passageway or bleed into the outlet of the condenser in a direction to oppose flow of hot gaseous refrigerant entering. the condenser inlet. Flow through the small passageway is sufficient however to substantially decrease pressure differential between the condenser inlet and outlet, and turbulence of refrigerant in the condenseris decreased.

The restricted passageway preferably has approximately the cross sectional area required to pass liquid refrigerant at a rate of flow corresponding to flow of gaseous refrigen ant into the inlet of the condenser when the modulating valve means is in position to pass hot gaseous refrigerant to the condenser inlet at minimum rate of flow. This approximation however is only a very rough one, and considerable deviations may be made from it without notable decrease in efiiciency of operation.

An outlet for liquid in the receiver is arranged below normal liquid level therein so that pressure upon the hot gas applied to the surface of liquid in the receiver forces liquid out of this line under pressure equivalent .to that of the hot gas in the upper part of the receiver, thus maintaining normal pressure upon the upstream side of, a pressure-reducing valve or capillary in the liquid outlet line between the receiver and an evaporator. Substantially normal pressure upon the pressure-reducingdevice thus maintains iiow through the device to the evaporator, and evaporation of normal quantities of liquid in the evaporator supplies the compressor with refigerant gas at pressure to maintain compressor efficiency.

It will be seen that this arrangement also provides for very easy start-up under conditions-of excess condenser capacity. In starting up, receiver pressure will be very low and hence the means for dividing and modulating the compressor efiiuent will divert a very large part of this efiiuent as hot gas into an upper part of the receiver while only a small part ofthe efiluent is passed to' the condenser. Under these conditions, the check valve responsive to receiver'pressure will be closed and only the small conduit or bleed opening will be open. Hot gas from an upper part of the receiver flows upward through the bleed opening or small conduit in a direction opposing the incoming first stream from the efiiuent dividing and modulating means, thus tending to cause stagnation in thecondenser with resulting reduced tubulence.

Liquid normally present in the lower part of the receiver is withdrawn under pressure from hot gas in the upper part of the. receiver to the pressure-reducing device and evaporator. Normally, this condition is very short in duration; and as soon as condenser pressure approaches receiver pressure, the system changes to a condition of increased flow through the condenser with the check valve open.

It will also be seen that this system and controls may be used for defrosting refrigeration equipment under conditions of low ambient temperature, or in fact in any 5, refrigeration and heat pump systems utilizing the compression cycle where excess condenser capacity occurs at some time in the cycle of operations.

The details of construction and operation may be best understood by reference to the following description of a preferred embodiment of the invention illustrated in the attached drawings, wherein like reference numerals are used to designate like parts in all figures:

FIG. 1 of the drawings illustrates schematically refrigeration equipment including a preferred type of control system embodying the present invention;

FIG. 2 illustrates an arrangement of heat pump equipment including a preferred control of the present invention;

FIG. 3 is a vertical section through a preferred valve useful as a means for dividing and modulating a con- =denser eflluenuand FIG. 4 is a section through one type of check valve useful in the control system of this invention.

In FIG. 1, the reference numeral 1 designates a conventional compressor having an outlet line 2 connected to conduct an efliuent from the compressor to a means for dividing and modulating the compressor effluent, illustrated as valve 3. Valve 3, asis best shown in FIG. 3, has an inlet port 2a, illustrated in PEG. 1 as connected to the compressor outlet line 2, an outlet port 4a connecti'ble to a first outlet line 4-, shown in FIG. 1, leading to the inlet of a conventional condenser 5.

Valve 3 also has a second outlet port 6a shown in FIG. 1 as connected to a second outlet line 6%} communicating with an upper part of a receiver 7 above a body of liquid 8 contained in the receiver. The valve 3 has a second fiowway, comprising a passageway g, a space 10 within the valve body, and a passageway 11, adapted to conduct fluid from inlet port 2:: to outlet port do. An annular valve seat 12 is disposed around passageway 11 and is cooperable with a valve-closure member 13 carried by valve stem 14 to close this passageway entirely or to modulate flow therethrough according to the distance between valve seat 12 and valve-closure member 13.

Valve 3 also has a first fiowway establishing communication between the inlet port 2 a and an outlet port 4a, shown in FIG. 1 to be connected to line 4, through a passageway 15. A cylindrical flow-restricting member 16 is carried upon valve stem 14 and is reciproca'ble into and out of passageway 15 to open the passageway 15 for full flow between ports 2a and 4a and into passageway 15 to obstruct free flow between these ports. Obstruction of flow is not complete, however, since the diameter of the passageway 15 exceeds that of the cylindrical flow-restricting member 16 suificiently to permit a minimum flow through the annulus 15a around flowrcstricting member 16 when the flow-restricting member 16 is in the passageway 15.

The valve has an actuator comprising a bellows 17 pressed in one direction by spring 18. Spring pressure upon bellows 1'7 is adjustable by nut 12 in a threaded section 20 of the valve body. The bellows 17 is thus expansible in response to reduction in receiver pressure communicated through line at} and port ea below a selected normal value determined by pressure of spring 18 so that valve stem 14 carried by the bellows is moved in one direction by reduction of such pressure to increase distance between valve seat 12 and valve-closure member 13 and at the same time to move the flow-restricting member 16 into the passageway 15 to obstruct flow between inlet port 2a and outlet port 4a. Valve stem 14 is moved in the reverse direction by increase in pressure in the receiver so that valve-closure member 13 is seated upon valve seat 12 and flow-restricting member 16 is Withdrawn from passageway 15 for a maximum distance when pressure in the receiver is above the selected normal value.

The condenser 5 is illustrated as located above a check valve, designated generally as 6, and the outlet of the condenser is connected to this check valve by a line 21, The check valve 6 in turn is located above receiver 7 and is connected to an upper part of receiver '7 by line 22. One of many types of check valve useful in this invention is shown in FIG. 4 and includes a body 23 having a flowway 2d therein and an annular valve seat 25 in the body around the flowway. A valve-closure member 26 is disposed in the body to move to and away from valveclosing position on valve seat 25 and is spring-pressed toward valve-closing position by spring 27. Spring pressure upon the valve-closure member is just sufiicient to move the weight of the valve-closure member. The valveclosure member has areas of such relative size exposed to condenser and receiver pressures that the valve is opened when condenser pressure is substantially equal to receiver pressure and is closed when receiver pressure exceeds condenser pressure.

The valve-closure member 2d has a small conduit therethrough adapted to transmit pressure from port 22a, shown in PEG. 1 as connected to line 22, to port 21a connected to line 21. This restricted passageway is constructed as a bleed opening comprising a passageway 3t? communicating with the interior of the body within valve seat 25 and with a space in the body around spring 27, and a second passageway 31 communicating with the flowway 24 above the valve-closure member and with the space around spring 27.

A liquid outlet line 32 is arranged to withdraw liquid from receiver '7 and to conduit the withdraw liquid refrigerant through pressure-reducing valve 33 to a conventional evaporator 34. An outlet line 35 is arranged to connect the outlet of evaporator 34 with the inlet of compressor 1.

In describing operation of the system illustrated in FIGS. 1, 2 and 3, we will assume, merely as an example, and not as limiting the invention, that this system is designed to operate at maximum efiiciency when receiver pressure is about 125 p.s.i.g.; that valve-closure member 13 will be fully seated upon valve seat 12 at this pressure; that the distance between valve seat 12 and valve-closure member 13 will be such at p.s.i.g. that flow through passageway 11 will be reduced to about one-half the rate of flow when valve-closure member 13 is at its maximum distance from the valve seat; and that the valve-closure member 13; will be at its maximum distance from valve seat 12 and fully open passageway 11 when pressure in the receiver falls to a selected minimum value assumed as 60 p.s.i.g.

It will be seen that under these conditions the flowrestricting member 16 is at its maximum limit of travel away from passageway 15 at p.s.i.g.; is withdrawn from passageway 15 for a distance sufiicient to permit about one-half the efiiuent to pass directly to the condenser inlet at 80 p.s.i.g.; and at 60 p.s.i.g., flow-restricting member 16 will be at its maximum limit of travel into pa sageway 15, thus permitting only minimum flow to the condenser through annulus 15a around flow-restricting member 16.

Pressure conditions at start-up under excess condenser capacity, such as may be caused by cold ambient fluid cooling the receiver, will be very low and will be assumed as 0 p.s.i.g. The temperature of liquid in the receiver also will be quite low. When the compressor starts, flow to the condenser inlet will be very small and only that due to leakage through annulus 15a around flow-restricting member 16, while valve-closure member 13 is approximately at its maximum distance from valve seat 12, thus opening passageway 11 widely. The check valve in the line between the condenser outlet and upper part of the receiver also is closed under these conditions. Almost all hot compressed gas from the compressor flows directly into the receiver and overlies colder liquid therein. Some of the gas also flows upward from the receiver through the restricted passageway to the condenser outlet, thus substantially equalizing condenser and receiver pressures, reducing velocity of flow through. the condenser. and decreasing the rate of heat transfer therein. At start-up, the condenser is completely empty and contains no condensed liquid since any liquid that may be condensed will have drained down through the check valve into the receiver.

Since the compressor capacity is much greater than flow through the restricted passageway, pressure of hot gas in the upper part of the receiver builds up rapidly; and this pressure is transmitted to the cold liquid in the bottom of the reeciver so that the liquid begins to flow at increasing rate through the pressure-reducing device to the evaporator.

This condition is normally of very short duration; and as soon as the receiver reaches a pro-set minimum head pressure determined by the compression of spring 18 at maximum extension, this pressure exerted upon bellows 17 of the valve actuator results in valve stem 14 moving to open the passageway 15 wider and throttle passageway condenser is very soon equalized with receiver pressure, Free communication be-' and the check valve 6 opens. tween the outletof condenser and the upper part'of receiver 7 is thus established through lines 21 and 22 and valve 6 so that pressure in the condenser and receiver are equalized and free flow of condensed liquid down from the condenser to the receiver is established. Partial stagw nation and reduction of turbulence in condenser 5 is thus maintained and the compressor continues to supply hot. gas at a rate exceeding the rate of totalcondensation in the condenser and receiver'sothat pressure continues to build up.

Further increase in pressure collapses bellows 17 further diverting a greater proportion of the total efliuent to the inlet of the condenser until a point of equilibrium is reached. At equilibrium, it has been. found that re: ceiver pressure is almost at the normal value, in this case assumed at 125 p.s.i.g. so that pressure on the upstream side of the pressure-reducing means is maintained near normal value and flow to theevaporator is at a'rate sufficient to provide cold gaseous refrigerant in the inlet of the compressor at sufiicien'tly high pressure to maintain compressor eificiency.

When condenser capacity is reduced to normal by increase in temperature of the ambient cooling fluid, receiver pressure rises to full normal value, assumed as 125 p.s.i.g., the valve-closure member 13 is seated upon valve seat 12 by full normal pressure in the receiver so.

that full flow of all compressor efiduent directly to the.

condenser inlet is restored.

In theheat pump system shown in FIG. 2, the outlet of a compressor 1 is connected through line 2 to an inlet port of valve 3, constructed as shownin FIG. 3. The outlet port'da of valve 3 is connected through a line 41 to a conventional four-way valve 4-2; which may be of either rotary, shuttle or other conventionaltype, 42 has a flow-directing valve member (not shown). adapted to direct flow from line 41 into line 43 .and from line 4-4 into line when the valve is in one position, and to direct flow from line 41 into line 44 and flow from line 43 into line 45' when the valve is in a second position, as is customary in heat pump systems. Line 45 is con-p nected to an inlet of compressor 1. a

A pair of heat exchangers 4-6 and-47 are provided, and alternately serve as condenser and evaporator ac cording to the position of four-wayvalve 42. In heat pump systems, it is customary to locate one of these; heat exchangers in an enclosure to be heated or cooled and the other outside the enclosure. For the purposes Valve of the following discussion, the heat exchanger 46 will be assumed to be located outside the enclosed space to be cooled and will serve as a condenser when the system is on cooling cycle.

Heat exchanger 46 is located at a level above receiver 7:: and is connected to the upper part of the receiver above a level of liquid do, normally present therein, by a line 48 inciuding a check valve 6 constructed according to PEG. 4. A bypass line 49 containing a solenoidoperated valve 51. and an expansion valve 50, communicates with the interior of receiver 7a below level of liquid therein and with line 43. betweencheck valve 6 and exchanger 4d.

Exchanger 47 alsocommunicates with a lower part of receiver 7a below liquid levelthrough line 52' containing an expansion valve 53.. A bypass line 54 containing check valve 55 and communicating with line 52 above and below expansion valve 53 is provided.

Port 621 of valve 3 is connectedby line 56'containing check valve 79 to an upper part of receiver 7a above liquid level therein. 7

This arrangement is useful in starting the cooling cycle under conditions ofexcess condenser and/or receiver capacity, such as may occur in winter when ambient temperature of air (or condensing medium) is low.

In starting up, pressure in the receiver and in valve 3' will be verylow, and it may be assumed that the flowrestricting member 16 has been moved by bellows 17 to its maximum distance inpassageway 15, thus closing passageway 1'5 except-for the small annulus 15a around the flow-restricting member 16. The valve-closure member 13 will be at its maximum distance from valve seat 12, thus opening the passageway iliwidely.

When the compressor 1 is started, the maximum amount of hot gas is passed through check valve in line se to the upper part of receiver 7:! since valve 70 is selected to open at a very low pressure below that at which the modulating action of bellows 17 begins. Pressure builds up in receiver 7a and is exerted through line 48 and check valve 6 upon theoutlet of heat exchanger 46, now serving as condenser.

At the same time a minimum. flow of hot compressor effluent is diverted through annulus 15a, outlet port 4a, line 41, four-way valve 42 and line 44: to the inlet of exchanger 46.

' through line. 52 and expansion valve 53 to the heat exchanger 47, now serving as evaporator. Cold gaseous effluent from the evaporator is passed through line 43, four-way valve 42 and line 45 to the inlet of compressor 1 at sufficiently high pressure to establish efficient operation of. the compressor. Start-up is thus easily accomplished even when the heat exchanger 46 is located in a very cold atmosphere.

When the apparatus shown is on heatingcycle, the heat exchanger 47 serves as condenser and exchanger 46 as evaporator. Hot gas from the outlet of compressor 1 flows through valve 3, line 41, four-way valve 42 and line 43 to exchanger 47. Under conditions which require heating of a room or enclosed space, the temperature of the enclosed space is usually high enough that no lack of head pressure exists. However, line 52 with valve 55 in theheating cycle approximate the function of line 48 and valve 6 in the cooling cycle.

In the heating cycle, if 'heat exchanger 47 (now acting as a condenser) were in a cooled room and had more capacity than necessar then valve 55 would close temporarily and valve 3 would shunt hot gas from compressor 1 directly into receiver 7a, increasing the pressure in receiver 70 and in line 49 to expansion valve 50, thus maintaining enough pressure difference across expansion valve 50 to maintain an efficient system. When pressure in heat exchanger 47 approaches that of receiver 7a, then check valve 55 opens and a normal heating cycle circulation begins. Valve 3 divides the flow between lines 41 and 56 in order to maintain a desired minimum head pressure on expansion valve 59.

This arrangement is also useful in the operation of air conditioning systems on cooling cycle under conditions of low ambient temperature. For the purposes of this explanation, the four-way valve 42 will be considered as in position to make the heat exchanger 46 a condenser. The condenser will be assumed to be located outside a building to be cooled and subjected to low atmospheric conditions or to low temperature of other ambient cooling fluid. The heat exchanger 47 will be considered as the evaporator and located inside the build- Under cool weather conditions, as for example when the atmosphere may be at a temperature of 60 F. or so, and the evaporator 47 is located inside a building, such as an auditorium or other room where relatively large quantities of heat are evolved because of the number of persons present or from other heat-producing sources, the temperature in the building may, for example, be about 80 F. t will of course be desirable to cool the building to about 70 F. under these conditions.

Condenser 46 has excess capacity because it is cooled at low ambient temperature. The liquid refrigerant So that is condensed and passed into receiver 7a will have a temperature lower than that required to provide sutficient pressure under equilibrium conditions to drive the quantity of fluid required for efficient operation through expansion valve 53 to evaporator 47.

As receiver pressure falls, the bellows 1'7 expands, moving the valve-closure member 13 ofif valve seat 12 to open passageway 11 which is connected to line 56. Increascd pressure is thus diverted to the receiver from the outlet of the compressor 1 and pressure of hot gas in the upper part of the receiver upon the cold liquid 8a becomes high enough that the liquid refrigerant is passed through expansion valve 53 at normal rate to restore the normal rate of cooling by evaporator 47. The check valve 6 remains closed under these conditions until pressure in receiver 7a and condenser 46 are approximately equalized. When pressure in receiver 46 is approximately the same as that in the upper part of the receiver, valve 6 opens and any liquid condensed in line 48 drains through into the receiver.

In normal operation, with check valve 6 open and the bypass line 56 closed by valve-closure member 13 seated on seat 12 in valve 3, condenser pressure will of course slightly exceed the pressure in the receiver; and if the condenser is located at substantially the same level as the receiver, this differential in pressure will be sufficient to drive any condensed liquid on into the receiver. The condenser may even be at a lower level than the receiver and the same result will be obtained.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the system.

t will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, What is claimed is:

1. In a cyclic system including a compressor, a condenser, a receiver, a pressure reducing device and an evaporator connected in sequence that improvement which comprises a valve having an inlet port connected to the com ressor outlet, a first outlet port connected to the condenser inlet, a second outlet port connected to an upper part of the receiver, a first flowway in the valve between the inlet port and first outlet port, a flow-restricting member carried by -a reciprocal valve stem to and from a position restricting flow through said first flowway, a second flowway between the inlet port and the second outlet port, a valve seat around the second flowway, a valve closure member carried by the valve stem to and from valve closing position on the valve seat, said valve closure member being moved to valve closing position as the flow-restricting member is moved from flow-restricting position; an actuator, responsive to receiver pressure, operatively connected to the valve stem to move the valve closure member from the valve seat through a distance substantially proportional to decrease in pressure in the receiver below a selected normal value; a check valve disposed to prevent flow into the condenser outlet; and a restricted passageway bypassing said check valve.

2. The system of claim ll wherein the flow-restricting member is cylindrical and of lesser diameter than a section of said first flowway to provide an annular flow path thereabout between the first conduit and second conduit and i reciprocaole into and out of said section of the flowway.

3. The system of claim 1 wherein the check valve comprises a body having a flowway therethrough; an annular valve seat around the flowway; and a valve-closure mem ber reciprocabie toward and away from valve-closing position on said seat disposed to be opened by equalization of condenser and receiver pressures; said restricted pas sageway being located in the valve closure member.

3. The system of claim 1 wherein the check valve comprises a body having a flowway therethrough, said flowway having two substantially axially aligned sections, a section substantially normal to the axially aligned section continuous with one of said sections and a section inclined from said substantially normal section continuous with the other of the axially aligned sections; an annular valve seat around said normal section; a valve-closure member reciprocable toward and away from valve-closing position on said seat; and a spring disposed to bias said valve-closure member toward seating position, said restricted passageway being in the closure member to establish restricted communication between the flowway on opposite sides of the vaive seat when the valve-closure member is seated.

5. In a cyclic system including a compressor, a condenser, a receiver, a pressure reducing device and an evaporator connected in sequence and means disposed to at least restrict flow into the condenser outlet, that improvement which comprises a valve having an inlet port connected to the compressor outlet, a first outlet port connected to the condenser inlet, a second outlet port connected to the receiver, a first flowway in the valve between the inlet port and first outlet port, a flow-restricting means within said valve movable to and from a position partially restricting flow through said first flowway while at all times permitting some flow through said first flowway, a second flowway between the inlet port and the second outlet port, a valve seat around the second flowway, a valve closure member movable to and from valve closing position on the valve seat, said valve closure memher being moved to valve closing position as the flowrestricting means is moved from flow-restricting position; and an actuator, responsive to receiver pressure, for moving the valve closure member from the valve seat through a distance substantially proportional to decrease in pressure in the receiver below a selected normal value.

6. The system of claim 5 wherein the valve actuator includes a spring-pressed bellows responsive to receiver 1 1 pressure without regard to pressure in other parts of the system.

7. In a cyclic refrigeration system including a compressor, a condenser, a receiver, a pressure reducing device and an evaporator connected in sequence, a three-way modulating valve including a body having an inlet port connected to the compressor outlet, a first outlet port connected to the condenser inlet, a second outlet port connected to an upper part of the receiver, a flow-controlling member in the body disposed to control flow from the inlet port to said first and second outlet ports and to increase flow through one of said outlet ports as flow is decreased through the other of said outlet ports, and a valve actuator connected to move the flow controlling member from a position preventing flow through the second outlet port responsive to receiver pressure; that improvement which comprises a check valve disposed to prevent flow from the second outlet port into the condenser outlet; and a restricted passageway bypassing said check valve.

8. In a cyclic system including a compressor, a condenser, a receiver, a pressurereducing device and an evaporator connected in sequence, that improvement which comprises a three-way modulating valve including a body having an inlet port connected to the compressor outlet, a first outlet port connected to the condenser inlet,

a second outlet port connected to an upper part of the' i2 below a selected normal value; a check valve disposed to prevent flow into the condenser outlet; and a restricted passageway bypassing said check valve.

9. In a cyclic system including a compressor, a condenser, a receiver, a pressure reducing device and an evaporator connected in sequence and means disposed to at least restrict flow into the condenser outlet, that improvement which comprises a three-Way modulating valve including a body having an inlet port connected to the compressor outlet, 3. first outlet port connected to the condenser inlet, a second outlet port connected to the receiver, a flow controlling means in the body disposed to control flow from the inlet to said first and second outlet ports, and to increase flow through one of said outlet ports as flow through the other outlet port is decreased, said flow controlling means only partially restricting flow through said first outlet port while at all times permitting some how through said first outlet port, and a valve actuator, including a spring loaded bellows responsive to receiver pressure without regard to pressure in other parts of the system connected to move the flow controlling member from a position preventing flow through the second outlet port for a distance substantially proportional to decrease in receiver pressure below a selected normal value.

References Cited by the Examiner UNITED STATES PATENTS 1,288,578 12/18 Hatfield 137-115 X 2,954,681 10/60 McCormack.

2,986,899 6/61 Schenk.

3,060,699 10/62 Tilney.

3,082,610 3/63 Marlo.

3,103,795 9/63 Tilney 62196 ROBERT A. OLEARY, Priirzary Examiner.

MEYER PERLIN, Examiner. 

1. IN A CYCLIC SYSTEM INCLUDING A COMPRESSOR, A CONDENSER, A RECEIVER, A PRESSURE REDUCING DEVICE AND AN EVAPORATOR CONNECTED IN SEQUENCE THAT IMPROVEMENT WHICH COMPRISES A VALVE HAVING AN INLET PORT CONNECTED TO THE COMPRESSOR OUTLET, A FIRST OUTLET PORT CONNECTED TO THE CONDENSER INLET, A SECOND OUTLET PORT CONNECTED TO AN UPPER PART OF THE RECEIVER, A FIRST FLOWWAY IN THE VALVE BETWEEN THE INLET PORT AND FIRST OUTLET PORT, A FLOW-RESTRICTING MEMBER CARRIED BY A RECIPROCAL VALVE STEM TO AND FROM A POSITION RESTRICTING FLOW THROUGH SAID FIRST FLOWWAY, A SECOND FLOWWAY BETWEEN THE INLET PORT AND THE SECOND OUTLET PORT, A VALVE SEAT AROUND THE SECOND FLOWWAY, A VALVE CLOSURE MEMBER CARRIED BY THE VALVE STEM TO AND FROM VALVE CLOSING POSITION ON THE VALVE SEAT, SAID VALVE CLOSURE MEMBER BEING MOVED TO VALVE CLOSING POSITION AS THE FLOW-RESTRICTING MEMBER IS MOVED FROM FLOW-RESTRICTING POSITION; AN ACTUATOR, RESPONSIVE TO RECEIVER PRESSURE, OP- 